Field of the Invention
The present invention relates to an imprint apparatus, a method of calibrating a correction mechanism, and a method of manufacturing an article.
Description of the Related Art
There is microfabrication technology for forming a pattern on a substrate according to an imprint process of molding an imprint material on the substrate according to a mold. This technology is also referred to as imprint technology and enables a pattern (structure) on the order of several nanometers to be formed on the substrate. For example, one type of imprint technology is a photocuring method. In an imprint apparatus adopting the photocuring method, first, a photocurable resin is supplied as an imprint material to a shot region on the substrate. Next, the resin on the substrate is molded using the mold. Then, the resin is cured by radiating light and released to form a pattern of the resin on the substrate. In the imprint technology, for example, there is a thermosetting method for curing a resin according to heat in addition to the photocuring method.
However, in an imprint apparatus adopting the above-described technology, a pattern shape error such as magnification, skew, or a trapezoid occurring in a semiconductor process may be included. Thus, when a base layer (base pattern) formed on the substrate in advance and a concave-convex pattern (pattern region) formed in a mold are superimposed, relative positions of a mark formed in the mold and a mark formed on the substrate are first measured using a detector. Next, the relative positions are corrected by deforming the mold based on a relative position difference. Here, a shape correction apparatus for deforming the mold at a precision of several nanometers or less is required to perform the superimposition of the pattern at high precision.
Therefore, Japanese Patent Laid-Open No. 2009-141328 discloses a shape correction apparatus in which an actuator for applying a compressive force to a side surface of a mold is disposed between the side surface of the mold and a support structure, the compressive force is measured using a force sensor installed between the actuator and the support structure, and feedback is controlled. In addition, the publication of Japanese Patent No. 4573873 discloses a method of obtaining a deformation parameter predicted to occur in a mold to minimize a dimension change between a record pattern on a mold and a reference pattern.
However, in a force sensor such as a load cell or a strain gauge for general use as disclosed in Japanese Patent Laid-Open No. 2009-141328, error sensitivity for an environmental change in temperature or humidity is high and a measurement error due to an offset or a gain change is likely to occur. In addition, because there is also a possibility of a measurement error occurring due to changes over time of an adhesive to be used when the strain gauge or the like is attached, it is difficult to maintain stable precision.
On the other hand, as disclosed in the publication of Japanese Patent No. 4573873, it is possible to correct a mold to a desired shape by measuring a plurality of marks at the time of alignment even when a sensor measurement error occurs. However, because it is difficult to correct the shape of the mold according to a command when the correction is affected by the sensor measurement error, the number of iterations of measurement increases until the residual converges and there is a possibility of the degradation of throughput.